Is it safe to use Generator function instead of normal function?

They are the same when yield is absent, of course not the same at the running phase.

function* add(x, y) {
    return x + y;
}  

var it = add(2, 3); 

it.next();

and

function add(x, y){
    return x + y;
}

add(2, 3);

As a habit, Is it safe and Okay to use them instead of normal functions? despite of performance.

via Mehdi Raash